Hydrazines find a variety of uses in silver halide photography. They have been used in negative working surface latent image forming silver halide emulsions to increase speed and/or contrast. They have been used in direct positive internal latent image forming emulsions as nucleating agents.
The use of hydrazines in negative working surface latent image forming emulsions to increase speed and contrast is taught by Trivelli et al U.S. Pat. No. 2,419,975. Increased contrast attributable to hydrazines in negative working surface latent image forming emulsions is believed to result from the promotion of infectious development.
Direct positive images can be produced using internal latent image forming emulsions by uniformly exposing the emulsions to light during development. This renders selectively developable the emulsion grains which were not imagewise exposed--that is, those grains which do not contain an internal latent image. Ives U.S. Pat. No. 2,563,785 recognized that the presence of hydrazines during processing can obviate the need for uniform light exposure. Hydrazines so employed with direct positive internal latent image forming emulsions are commonly referred to as nucleating agents. Occasionally the term "fogging agent" is employed, but the term "nucleating agent" is preferred, since nucleating agents do not produce indiscriminate fogging.
The most efficient hydrazines employed in silver halide photographic systems employ a combination of substituents to balance activity and stability. The stability of hydrazines is increased by attaching directly to one of the nitrogen atoms a tertiary carbon atom, such as the carbon atom of an aromatic ring. The art has long recognized that the activity of these stabilized hydrazines can be increased by the direct attachment of an acyl group to the remaining nitrogen atom. Thus, the most commonly employed hydrazines are arylhydrazides.
The following are illustrative of specific arylhydrazides employed with negative working surface latent image forming silver halide emulsions primarily to increase contrast:
______________________________________ P-1 Takada et al U.S. Pat. No. 4,168,977 P-2 Takada et al U.S. Pat. No. 4,224,401 P-3 Mifune et al U.S. Pat. No. 4,243,739 P-4 Mifune et al U.S. Pat. No. 4,272,614 P-5 Mifune et al U.S. Pat. No. 4,323,643 ______________________________________
The arylhydrazide can be incorporated directly in a photographic element or in a processing solution for the element. A preferred processing solution is disclosed in the following patent:
______________________________________ P-6 Nothnagle U.S. Pat. No. 4,269,929. ______________________________________
The following are illustrative of specific acylhyrazides employed with direct positive internal latent image forming emulsions to act as nucleating agents:
______________________________________ P-7 Whitmore U.S. Pat. No. 3,227,552 P-8 Leone 10024. al U.S. Pat. No. 4,030,925 P-9 Leone et al U.S. Pat. No. 4,031,127 P-10 Leone et al U.S. Pat. No. 4,080,207 P-11 Tsujino et al U.S. Pat. No. 4,245,037 P-12 Hirano et al U.S. Pat. No. 4,255,511 P-13 Adachi et al U.S. Pat. No. 4,266,013 P-14 Leone U.S. Pat. No. 4,276,364 P-15 Hirano et al U.K. Pat. App. 2,087,057A ______________________________________ RD-1 Research Disclosure, Vol. 151, November 1976, Item 15162. (Note also reduction sensitization effect, left column, page 77.) RD-2 Sidhu et al Research Disclosure, Vol. 176, December 1978, Item 17626 December 1978, Item 17626 (Research Disclosure and Product Licensing Index were publications of Industrial Opportunities Ltd.; Homewell, Havant; Hampshire, P09 1EF, United Kingdom Research Disclosure is now published at Emsworth Studios, 535 West End Avenue, New York, New York 10024.)
For the most part these nucleating agents contain a moiety for promoting adsorption to the silver halide grain surfaces and are therefore preferably incorporated directly within the silver halide emulsion. Unadsorbed nucleating agents, such as those disclosed by P-7, for example, can be present in other photographic element layers or in processing solutions, if desired. Unadsorbed nucleating agents incorporated in photographic elements are often ballasted.
The above arylhydrazide nucleating agents share a common characteristic in that one hydrogen is attached to each of the .alpha. and .beta. nitrogen atoms. Tsujino et al U.S. Pat. No. 4,294,919 differs from the above patents in adding in one optional form a second hydrazino moiety which can be fully substituted; however, the .alpha. and .beta. nitrogen atoms attached to the acyl moiety each require one hydrogen. Von Konig et al U.S. Pat. No. 4,139,387 discloses a sulfocarbazide used as a nucleating agent. As generically disclosed both an acyl moiety and another moiety can be attached to a single nitrogen atom. No specific illustration is provided.
Borsche and Ockinga "Regarding the Relationships Between Quinone Hydrazones and p-Oxyazo Compounds", Annalen der Chemie, Vol. 340, 1905, pp. 85-101, describes the preparation of arylhydrazines and their derivatives, including 1-benzoyl-2-phenylsulfonyl-2-(4-hydroxyphenyl) hydrazide. Hantzsch and Glogauer "Regarding the Addition Products of Azo and Diazo Elements with Benzenesulfinic Acid", Berichte der Deutschen Chemischen Gesellschaft, Vol. I, 1897, pp. 2548-2559, discloses the preparation of 1-carbamoyl-2-phenyl-2-phenylsulfonylhydrazine.
Lincoln and Heseltine U.S. Pat. Nos. 3,615,615 and 3,854,956 disclose heterocyclic nuclei of the type found in cyanine dyes substituted at the quaternized nitrogen atom with an arylsulfohydrazonoalkyl substituent. These compounds are disclosed to be useful as nucleating agents in direct positive internal latent image forming silver halide emulsions.
Takahashi et al U.K. Pat. App. No. 2,097,140A discloses a coupler containing at the coupling site a development accelerating group preferably of the formula: ##STR1## wherein R.sub.1, is formyl, acyl, sulfonyl, alkoxycarbonyl, carbamoyl or sulfamoyl, R.sub.2 is H, acetyl, ethoxycarbonyl, or methanesulfonyl, R.sub.3 and R.sub.4 are each H, halogen, or C.sub.1-4 alkyl or alkoxy, and X a linking group containing a hetero atom and can comprise a heterocyclic ring linked to the residue by the hetero atom.